The poll released today – based on a mix of registered voters and likely voters (more about that later) – showed Boxer with a six-point lead over former Hewlett-Packard CEO Carly Fiorina, 47% to 41%. Note that Boxer still isn’t above the 50% threshold.

Since the Field Poll in July, which showed a tighter race, Fiorina’s support has slipped a bit, Boxer’s has remained unchanged and the portion of undecided voters has risen three percentage points.

The poll turned up clear anti-incumbent frustration: 67% of Fiorina supporters said their vote preference was more of a vote against Boxer than for Fiorina. Nearly a third, 31%, of Boxer supporters said their vote was more against Fiorina.

The poll, based on a survey of 857 registered voters, including 599 deemed likely to vote in November, has an error margin of 4.1 percentage points.

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Washington Wire is one of the oldest standing features in American journalism. Since the Wire launched on Sept. 20, 1940, the Journal has offered readers an informal look at the capital. Now online, the Wire provides a succession of glimpses at what’s happening behind hot stories and warnings of what to watch for in the days ahead. The Wire is led by Reid J. Epstein, with contributions from the rest of the bureau. Washington Wire now also includes Think Tank, our home for outside analysis from policy and political thinkers.